Our major focus has been on processes occurring in nerve axons and endings (i.e., axonal transport and secretion). These studies have emphasized the role of cytoskeletal proteins in these processes, and have characterized these protein interactions with membranes. Regulation of neurofilaments by calcium-activated proteases, and intra-vesicular pH by membrane-bound ATPases have been demonstrated. Four new techniques have been developed: 1) An HPLC system for analysis of taurine, 2) An iso-osmolar density gradient for secretory vesicle isolation, 3) A covalent-labeling method to study retrograde axonal transport in vivo, and 4) a new histochemical method for thiols and disulfides.